# Stint
# Copyright 2018 Status Research & Development GmbH
# Licensed under either of
#
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
#
# at your option. This file may not be copied, modified, or distributed except according to those terms.

import ../stint, unittest, test_helpers

template chkAddition(chk, a, b, c, bits: untyped) =
  block:
    let x = stint(a, bits)
    let y = stint(b, bits)
    chk x + y == stint(c, bits)

template chkInplaceAddition(chk, a, b, c, bits: untyped) =
  block:
    var x = stint(a, bits)
    x += stint(b, bits)
    chk x == stint(c, bits)

template chkSubstraction(chk, a, b, c, bits: untyped) =
  block:
    let x = stint(a, bits)
    let y = stint(b, bits)
    chk x - y == stint(c, bits)

template chkInplaceSubstraction(chk, a, b, c, bits: untyped) =
  block:
    var x = stint(a, bits)
    x -= stint(b, bits)
    chk x == stint(c, bits)

template chkNegation(chk, a, b, bits: untyped) =
  chk -stint(a, bits) == stint(b, bits)

template chkAbs(chk, a, b, bits: untyped) =
  chk stint(a, bits).abs() == stint(b, bits)

template testAddSub(chk, tst: untyped) =
  tst "addition":
    chkAddition(chk, 0'i8, 0'i8, 0'i8, 128)
    chkAddition(chk, high(int8) - 17'i8, 17'i8, high(int8), 128)
    chkAddition(chk, low(int8) + 17'i8, 17'i8, low(int8) + 34'i8, 128)
    chkAddition(chk, high(int16) - 17'i16, 17'i16, high(int16), 128)
    chkAddition(chk, low(int16) + 17'i16, 17'i16, low(int16) + 34'i16, 128)
    chkAddition(chk, high(int32) - 17'i32, 17'i32, high(int32), 128)
    chkAddition(chk, low(int32) + 17'i32, 17'i32, low(int32) + 34'i32, 128)
    chkAddition(chk, high(int64) - 17'i64, 17'i64, high(int64), 128)
    chkAddition(chk, low(int64) + 17'i64, 17'i64, low(int64) + 34'i64, 128)

  tst "inplace addition":
    chkInplaceAddition(chk, 0'i8, 0'i8, 0'i8, 128)
    chkInplaceAddition(chk, high(int8) - 17'i8, 17'i8, high(int8), 128)
    chkInplaceAddition(chk, low(int8) + 17'i8, 17'i8, low(int8) + 34'i8, 128)
    chkInplaceAddition(chk, high(int16) - 17'i16, 17'i16, high(int16), 128)
    chkInplaceAddition(chk, low(int16) + 17'i16, 17'i16, low(int16) + 34'i16, 128)
    chkInplaceAddition(chk, high(int32) - 17'i32, 17'i32, high(int32), 128)
    chkInplaceAddition(chk, low(int32) + 17'i32, 17'i32, low(int32) + 34'i32, 128)
    chkInplaceAddition(chk, high(int64) - 17'i64, 17'i64, high(int64), 128)
    chkInplaceAddition(chk, low(int64) + 17'i64, 17'i64, low(int64) + 34'i64, 128)

  tst "substraction":
    chkSubstraction(chk, 0'i8, 0'i8, 0'i8, 128)
    chkSubstraction(chk, high(int8) - 17'i8, 17'i8, high(int8) - 34'i8, 128)
    chkSubstraction(chk, -high(int8), -high(int8), 0'i8, 128)
    chkSubstraction(chk, high(int16) - 17'i16, 17'i16, high(int16) - 34'i16, 128)
    chkSubstraction(chk, -high(int16), -high(int16), 0'i16, 128)
    chkSubstraction(chk, high(int32) - 17'i32, 17'i32, high(int32) - 34'i32, 128)
    chkSubstraction(chk, -high(int32), -high(int32), 0'i32, 128)
    chkSubstraction(chk, high(int64) - 17'i64, 17'i64, high(int64) - 34'i64, 128)
    chkSubstraction(chk, -high(int64), -high(int64), 0'i64, 128)

  tst "inplace substraction":
    chkInplaceSubstraction(chk, 0'i8, 0'i8, 0'i8, 128)
    chkInplaceSubstraction(chk, high(int8) - 17'i8, 17'i8, high(int8) - 34'i8, 128)
    chkInplaceSubstraction(chk, -high(int8), -high(int8), 0'i8, 128)
    chkInplaceSubstraction(chk, high(int16) - 17'i16, 17'i16, high(int16) - 34'i16, 128)
    chkInplaceSubstraction(chk, -high(int16), -high(int16), 0'i16, 128)
    chkInplaceSubstraction(chk, high(int32) - 17'i32, 17'i32, high(int32) - 34'i32, 128)
    chkInplaceSubstraction(chk, -high(int32), -high(int32), 0'i32, 128)
    chkInplaceSubstraction(chk, high(int64) - 17'i64, 17'i64, high(int64) - 34'i64, 128)
    chkInplaceSubstraction(chk, -high(int64), -high(int64), 0'i64, 128)

  tst "negation":
    chkNegation(chk, 0, 0, 128)
    chkNegation(chk, 128, -128, 128)
    chkNegation(chk, 127, -127, 128)
    chkNegation(chk, 32768, -32768, 128)
    chkNegation(chk, 32767, -32767, 128)
    chkNegation(chk, 2147483648, -2147483648, 128)
    chkNegation(chk, 2147483647, -2147483647, 128)

    let x = int64.high.i128
    chk -x == -9223372036854775807'i64.i128

    let y = int64.low.i128
    let z = int64.high.i128 + 1.i128
    chk -y == z

  tst "absolute integer":
    chkAbs(chk, 0, 0, 128)
    chkAbs(chk, -127, 127, 128)
    chkAbs(chk, -32767, 32767, 128)
    chkAbs(chk, -1, 1, 128)
    chkAbs(chk, 1, 1, 128)
    chkAbs(chk, 127, 127, 128)
    chkAbs(chk, 32767, 32767, 128)
    chkAbs(chk, -2147483647, 2147483647, 128)
    chkAbs(chk, 2147483647, 2147483647, 128)
    chkAbs(chk, -9223372036854775807, 9223372036854775807, 128)
    chkAbs(chk, 9223372036854775807, 9223372036854775807, 128)

static:
  testAddSub(ctCheck, ctTest)

proc main() =
  # Nim GC protests we are using too much global variables
  # so put it in a proc
  suite "Wider signed int addsub coverage":
    testAddSub(check, test)

  suite "Testing signed addition implementation":
    test "In-place addition gives expected result":

      var a = 20182018.stint(256)
      let b = 20172017.stint(256)

      a += b

      check a == (20182018'i64 + 20172017'i64).i256

    test "Addition gives expected result":

      let a = 20182018.stint(256)
      let b = 20172017.stint(256)

      check a+b == (20182018'i64 + 20172017'i64).i256

    test "When the low half overflows, it is properly carried":
      # uint8 (low half) overflow at 255
      let a = 100.stint(256)
      let b = 100.stint(256)

      check a+b == 200.i256

  suite "Testing signed substraction implementation":
    test "In-place substraction gives expected result":

      var a = 20182018.stint(256)
      let b = 20172017.stint(256)

      a -= b

      check a == (20182018'i64 - 20172017'i64).i256

    test "Substraction gives expected result":

      let a = 20182018.stint(256)
      let b = 20172017.stint(256)

      check: a-b == (20182018'i64 - 20172017'i64).i256

main()